Optimization and Modeling of Simultaneous Adsorption of Cr(VI) and Phenol Onto Dowex 1X8 Ion Exchange Resin: Kinetic and Thermodynamic Studies

This work investigates the optimization of simultaneous adsorption of Cr(VI) and phenol using Dowex 1X8 ion exchange resin. The morphology of adsorbent was examined under scanning electron microscope and Fourier transform infrared spectroscopy spectrum. Central composite design (CCD) was chosen to examine the effects of pH, adsorbent dose, initial concentrations of Cr(VI) and phenol in the adsorption process. The maximum Cr(VI) adsorption capacity (41.291 mg/g) and the maximum phenol adsorption capacity (5.69 mg/g) were obtained at initial pH (9.6), resin dose (0.621 g), initial Cr(VI) concentration (290 mg/L) and initial phenol concentration (145 mg/g). The CCD data were employed to develop the artificial neural network (ANN). The determination coefficients suggest the reliability of the developed ANN models. The statistical results reveal that CCD has the best performance for prediction compared with ANN. The influence of ionic strength on adsorption process was investigated separately. The increase of ionic strength was slightly decreased the adsorption efficiency of Cr(VI) and facilitates the adsorption of phenol on the surface of adsorbent. The experiments demonstrated that Dowex 1X8 resin had a good potential in the efficient removal of Cr(VI) and phenol from real wastewaters collected from tannery factory. Kinetic models were adjusted to experimental data, and the pseudo-second-order model presented the best fitting. Thermodynamic study depicted that adsorption of Cr(VI) and phenol onto Dowex 1X8 was spontaneous and endothermic.